Pyrotechnic fastener seat arrangement for unbelted occupant protection

ABSTRACT

A seat assembly including a seat pan that drops vertically in the event of a frontal impact event to help safeguard against the head of an unbelted seat occupant striking the headliner, windshield or other components of the vehicle. The seat assembly includes a seat pan attached to a seat track. The seat track further includes an attachment bracket. A swing linkage movably connects the seat pan with the seat track by a movable fastener. A slot is formed in the bracket through which at least a part of the movable fastener passes. A pyrotechnic fastener also attaches the swing linkage to the bracket. In a frontal impact event, the pyrotechnic fastener is caused to explode thus separating the pyrotechnic fastener into two parts and allowing the swing linkage and its attached seat pan to drop vertically relative to the seat track and lowering the unbelted occupant.

TECHNICAL FIELD

The disclosed inventive concept relates generally to safety systems forvehicle seats. More particularly, the disclosed inventive conceptrelates to a seat having a pyrotechnic fastener attachment and swinglinkage arrangement that allows the seat pan of a vehicle to dropvertically in an impact event.

BACKGROUND OF THE INVENTION

Under certain circumstances, particularly in a frontal impact event,some vehicles tend to rise. While the degree of rise of a vehicle mayvary according to vehicle type, the rise is itself a common phenomenon.In such a situation an unbelted occupant tends to move vehicle forwardtoward the front of the seat. This is so because no belt is in use thatwould otherwise restrict forward movement. In addition, because adeployed airbag ordinarily presses against either the front or the sideof the occupant and thus prevents the unbelted occupant from movingfurther forward, the vehicle rise can push an unbelted occupant upwardinside the vehicle compartment.

Particularly, and according to known seat designs in today's vehicles,the rise of the vehicle in a frontal impact event results in a number ofpotential challenges to the unbelted seat occupant. A main concern is,if the seated occupant is unbelted, the head of the driver or of thefront seat passenger may contact the roof, the visor, the headliner orthe windshield during a frontal impact event.

Since the current seat design is constrained to be adjustable for alldifferent impact modes, it may be that an adjustable seat pan height cansignificantly enhance unbelted occupant safety protection, in additionto the optimized restraints system. However, current seat designs do notpermit for the adjustment of seat pan height in an impact event.

As in so many areas of vehicle technology, there is always room forimprovement related to improving the safety of unbelted seat occupantsin vehicles in an impact event.

SUMMARY OF THE INVENTION

The disclosed inventive concept overcomes the problems associated withknown safety systems directed to unbelted seat occupants. The disclosedinventive concept provides a seat assembly for a vehicle that comprisesa seat pan attached to a seat track.

The seat pan includes a rear portion and the seat track includes a rearportion. The rear portion of the seat pan is attached to the rearportion of the seat track by an arm. The seat track further includes aninner track and an attachment bracket attached to the inner track.

A swing linkage movably connects the seat pan with the seat track. Theswing linkage is movably attached to the attachment bracket of the seattrack by a movable fastener. A slot is formed in the bracket adjacentthe movable fastener. The slot is formed substantially perpendicularlyto the long axis of the seat track.

A pyrotechnic fastener also attaches the swing linkage to the bracket.In a frontal impact event, the pyrotechnic fastener is caused to firethus separating the pyrotechnic fastener and allowing the swing linkageand the attached seat pan to drop vertically relative to the seat trackand lowering the unbelted occupant. With the seat pan repositioned, theunbelted occupant's head is prevented from contacting any hard or softsurfaces inside the vehicle compartment.

The deployment of the pyrotechnic fastener may be calibrated based on anumber of inputs. Accordingly the disclosed inventive concept offersamong several advantages flexibility in adjusting the seat pan height indifferent impact situations for improved unbelted occupant safetyprotection.

The above advantages and other advantages and features will be readilyapparent from the following detailed description of the preferredembodiments when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this invention, reference shouldnow be made to the embodiments illustrated in greater detail in theaccompanying drawings and described below by way of examples of theinvention wherein:

FIG. 1 shows a side view of a seat pan and seat track arrangementaccording to the known art;

FIG. 2 illustrates a side view of a swing linkage for connecting theseat pan to the seat track according to the known art;

FIG. 3 is a side view of a swing linkage connecting a seat pan to a seattrack according to the disclosed inventive concept;

FIG. 4 shows a sectional view of the swing linkage connected to the seattrack taken along line 4-4 of FIG. 3 before an impact event;

FIG. 5 illustrates a side view of a seat pan and seat track arrangementaccording to the disclosed inventive concept;

FIG. 6 is similar to the view shown in FIG. 4 of the swing linkage inrelation to the seat track but showing the pyrotechnic fastener beingsevered during an impact event and the swing linkage consequently beingdropped vertically;

FIG. 7 is a side view of the swing linkage after the pyrotechnicfastener has been severed; and

FIG. 8 is a side view of the seat pan and the seat track having theswing linkage shown in FIG. 5 but illustrating the seat pan havingdropped to its lowered position following the severing of thepyrotechnic fastener after an impact event.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following figures, the same reference numerals will be used torefer to the same components. In the following description, variousoperating parameters and components are described for differentconstructed embodiments. These specific parameters and components areincluded as examples and are not meant to be limiting.

In general, the disclosed invention provides a practical and economicalsolution to one of the problems related to providing safety to anunbelted seat occupant. The disclosed inventive concept overcomes theproblems commonly associated with known designs.

FIG. 1 illustrates a seat assembly according to the prior art, generallyillustrated as 10. The seat assembly 10 includes a seat pan 12 and aseat track 14. Toward the rear of the assembly 10 the seat pan 12 isattached to the seat track 14 at one end by an arm 15. The arm 15 isattached to the seat pan 12 by a fastener 16 and is attached to the seattrack 14 by a fastener 17. Toward the front of the seat assembly 10 theseat pan 12 is attached to the seat track 14 by a swing linkage 18.

The seat track 14 includes an inner seat track 20. The inners seat track20 includes a bracket 22. The bracket 22 is fastened to the inner seattrack 20.

One end of the swing linkage 18 is attached to the upper portion of thebracket 22 by a fastener 24. The other end of the swing linkage 18 isattached to the seat pan 12 by a mechanical fastener 26.

FIG. 2 illustrates a side view of the swing linkage 18 of the priorshown in FIG. 1 in relation to the bracket 22 and the inner seat track20. The swing linkage 18 has a hole 28 formed in its uppermost end toaccommodate the fastener 26 used to secure the swing linkage 18 to theseat pan 12.

As is understood by referring to FIGS. 1 and 2, the prior art teachesthat the height of the seat pan 12 relative to the seat track 14 issubstantially fixed. In an impact event of any type this arrangement,and the height defined thereby, is designed to remain intact.

Conversely, the disclosed inventive concept is designed to allow theforward end of the seat pan to drop vertically in a frontal impactevent. Particularly, and with reference to FIGS. 3 through 8, thedisclosed inventive concept is structured so as to overcome may of thechallenges associated with known designs.

Referring to FIG. 3, a side view of a swing linkage 50 is shown. Alsoillustrated is a side view of a seat track 52 having an inner track 54.Attached to the inner track 54 is a bracket 56. The bracket 56 hasformed therein a substantially vertical slot 58.

The swing linkage 50 has a rearward end 60 having a fastener hole 62formed therein. The swing linkage 50 has a forward end 64. A fastener 65attaches the swing linkage 50 to the bracket 56. The fastener 65includes a bolt head 66. The width of the shaft of the fastener 65 isnarrower than the width of the vertical slot 58 but the width of thebolt head 66 of the fastener 65 is wider than the width of the openingdefined by the vertical slot 58.

A pyrotechnic fastener 67 attaches the swing linkage 50 to the bracket56. The pyrotechnic fastener 67 is also known as an explosive bolt or asa pyro bolt. Typically a nut and bolt assembly, the pyrotechnic fastener67 includes a pyrotechnic charge of some type (not shown) that isembedded within the bolt portion of the assembly. A common andnon-limiting example of a pyrotechnic charge is RDX such as explosivenitroamine. As is known, the charge is ignited typically by a remoteinitiator 68 that sends an electric current to the pyrotechnic fastener67 causing it to be severed.

Referring to FIG. 4, an end view of the swing linkage 50, the seat track52, and the bracket 56 is illustrated prior to an impact event. Thepyrotechnic fastener 68 retains the swing linkage 50 in its raisedposition relative to the bracket 56 as would normally be the case. Thefastener 66 is illustrated as also holding the swing linkage 50 relativeto the bracket 56.

FIG. 5 illustrates a side view of an assembly, generally illustrated as70, that incorporates the swing linkage 50 of the disclosed inventiveconcept. The assembly 70 includes a seat pan 72. The rearward end of theswing linkage 50 is attached to the seat pan 72 by a fastener 74. Theseat pan 72 is also attached to the seat track 52 by an arm 76. The arm76 is attached to the seat track 52 by a fastener 78. The arm 76 isattached to the seat pan 72 by a fastener 80.

In a frontal impact event the remote igniter 68 is sent a signal by acentral processing unit (not shown) that the impact occurred. The remoteigniter 68 then sends an electric current to the pyrotechnic fastener 67causing it to explode and sever into two parts, 67A and 67B, asillustrated in FIG. 6. The deployment of pyrotechnic fastener 67 can becalibrated according to specific vehicle.

With the pyrotechnic fastener 67 thus severed, the swing linkage 50falls vertically as illustrated in FIG. 6. As shown also in FIG. 7,because the bolt head 66 of the shoulder of the fastener 65 is widerthan the width of the vertical slot 58, the swing linkage 50 remainsattached to the bracket 54.

The result of the vertical drop of the swing linkage 50 on the profileof the assembly 70 is shown in FIG. 8 in which a side view of the seatpan 72 and the seat track 52 is shown. As illustrated, the forward partof the seat pan 72 is now vertically lower than its pre-impact state,thus demonstrating how the disclosed inventive concept preciselycontrols the height of the seat pan 72 for different crash conditions atspecific times. The disclosed inventive concept allows the seat pan 72to drop vertically relative to the seat track 52 while still remainingattached thereto.

Once the swing linkage 50 slides down relative to the bracket 56 theseat pan 72 will drop as well for the same distance, consequentlylowering the pelvis of the unbelted seat occupant. The unbelted seatoccupant is thus prevented from making contact with any hard or softsurfaces above the head inside the vehicle compartment in a frontalimpact event. The disclosed inventive concept accordingly offersflexibility in adjusting the height of the seat pan 72 in differentimpact events for improved unbelted occupant safety protection.

The disclosed invention as set forth above overcomes the challengesfaced by known seat systems in which unbelted occupants may be present.However, one skilled in the art will readily recognize from suchdiscussion, and from the accompanying drawings and claims that variouschanges, modifications and variations can be made therein withoutdeparting from the true spirit and fair scope of the invention asdefined by the following claims.

What is claimed is:
 1. A seat assembly for a vehicle comprising: a seatpan; a seat track; a bracket attached to said track; a swing linkage; afastener attaching said swing linkage to said bracket; a slot formed insaid bracket adjacent said fastener; and an explodable fastener having apyrotechnic charge, said explodable fastener being attached to saidswing linkage.
 2. The seat assembly for a vehicle of claim 1 whereinsaid slot is formed in said bracket substantially perpendicularly withrespect to said seat track.
 3. The seat assembly for a vehicle of claim1 wherein said pyrotechnic fastener is a nut and bolt assembly.
 4. Theseat assembly for a vehicle of claim 1 wherein said pyrotechnic fasteneris deployable and wherein the deployment of said pyrotechnic fastener iscalibrated.
 5. The seat assembly for a vehicle of claim 1 wherein saidseat track includes an inner seat track and said bracket is attached tosaid inner seat track.
 6. A seat assembly for a vehicle comprising: aseat pan; a seat track; a swing linkage; a fastener attaching said swinglinkage to said track; a slot formed in said frame adjacent saidfastener; and an explodable fastener attached to said swing linkage; anda remote initiator attached to said explodable fastener.
 7. The seatassembly for a vehicle of claim 6 wherein said seat track includes abracket and wherein said fastener is attached to said bracket.
 8. Theseat assembly for a vehicle of claim 7 wherein said seat track includesan inner seat track and said bracket is attached to said inner seattrack.
 9. The seat assembly for a vehicle of claim 7 wherein said slotis formed in said bracket.
 10. The seat assembly for a vehicle of claim9 wherein said slot is formed in said bracket substantiallyperpendicularly with respect to said seat track.
 11. The seat assemblyfor a vehicle of claim 9 wherein said pyrotechnic fastener is deployableand wherein the deployment of said pyrotechnic fastener is calibrated.12. The seat assembly for a vehicle of claim 6 wherein said pyrotechnicfastener is a nut and bolt assembly.
 13. The seat assembly for a vehicleof claim 6 wherein said seat pan has a rear portion and said seat trackhas a rear portion and wherein said rear portion of said seat pan isattached to said rear portion of said seat track by an arm.
 14. A seatassembly for a vehicle comprising: a seat pan; a seat track, said trackhaving a long axis; a bracket attached to said track; a swing linkage; afastener attaching said swing linkage to said bracket; a slot formed insaid bracket adjacent said fastener, said slot being substantiallyperpendicular to said long axis of said track; and an explodablefastener attached to said swing linage, said explodable fastenerincluding a bolt, said bolt having a pyrotechnic charge.
 15. The seatassembly for a vehicle of claim 14 wherein said seat track includes aninner seat track and said bracket is attached to said inner seat track.16. The seat assembly for a vehicle of claim 14 wherein said swinglinkage includes an upper portion and said bracket includes an upperportion and wherein said pyrotechnic fastener connects said upperportion of said swing linkage with said upper portion of said bracket.17. The seat assembly for a vehicle of claim 14 wherein said seat panhas a rear portion and said seat track has a rear portion and whereinsaid rear portion of said seat pan is attached to said rear portion ofsaid seat track by an arm.
 18. The seat assembly for a vehicle of claim14 wherein said pyrotechnic fastener is a nut and bolt assembly.
 19. Theseat assembly for a vehicle of claim 18 wherein said pyrotechnicfastener is deployable and wherein the deployment of said pyrotechnicfastener is calibrated.